The present invention relates to the field of minimally invasive, percutaneous procedures such as angioplasty. In particular, the invention relates to a distal filter for use during such a procedure.
Angioplasty, atherectomy and stent placement, among other procedures, have become well accepted for treatment of coronary lesions. These procedures are often performed as an alternative to coronary bypass. It is also possible, however, that a saphenous vein graft, which is used to bypass coronary lesions, may itself develop a lesion. These lesions may also be treated by minimally invasive procedures such as angioplasty, atherectomy and/or stent placement.
When lesions are treated by these minimally invasive, percutaneous methods, it is possible that particles of plaque, thrombus or other material may break loose from the lesion and drift distally into the smaller coronary arteries. When these minimally invasive methods are performed on native arteries, the plaque or thrombus released during the procedure rarely cause embolization. When these procedures are performed on saphenous vein grafts, however, the incidence of embolism due to the breaking off of plaque or thrombus from the vein graft is substantially greater than from native arteries.
The increased incidence of embolization is believed to be due, at least in part, to the larger diameter of the bypass graft relative to the native artery. The larger diameter of the graft results in a slower blood flow velocity through the graft than the native artery. In addition, the plaque and thrombus of vein grafts is somewhat more fragile than that found in native arteries.
As the difference in embolism associated with treatment of native arteries and vein grafts has been noted, it would be desirable to develop techniques to reduce embolism associated with treatment of vein graft lesions. Additionally, where stent placement or other minimally invasive treatments are performed on the carotid artery, it would be desirable to limit the drift of plaque and thrombus toward the brain.